Dr Lukas Payne

(he/him)

MPhys PhD (Cardiff)

Publication

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Research

Nanoparticles (NPs) are ubiquitous in our environment, from those naturally occuring such as nanoscale biological objects like liposomes and virions (individual viral bodies), to those generated as waste from aging plastic or from industrial applications, to metallic nanoparticles used various applications/research. In most cases, understanding NP physical, chemical, and optical properties is an important requirement to better develop NP production, application, or waste managment. A significant point of interest in my work to date has been the development of a linear optical microscopy and analysis methodology, the Optical Nanosizer (ON), to overcome the capabilites currently missing from existing technologies addressing NP characterisation. Specifically, the ON seeks to provide the accuracy of TEM in terms of NP shape/size measurements, with the throughput of industry-standard techniques like dynamic light scattering. I am interested in applying this technology in the NP manufacturing sector, including biologics, such as liposomes, exosomes, and vaccines, as well as in water research for detection and characterisation of NP wastes. In addition the ON probes the linear optical properties of NPs, including the phenomenon of localised surface plasmon exhibited by metal NPs, another interesting area of research in its own right.

I am currently working on direct laser writing (photolithography) in the visible (near-UV) at a wavelength of 405nm. Photolithography has become the dominant technique in semi-conductor manufacturing of microprocessors, but is also used more generally in fabrication of microstructured systems. The setup we are building now will be used to write 3D magnetic structures to study domain wall pinning and other nanoscale magnetic phenomena. Presently, improvements in diffraction-limited photolithography tend to focus on reducing the lateral resolution of the writing, i.e. reducing the lateral dimensions of a single written point, not unlike a single dot on a printed page. This can be achieved by reduction of the operating wavelength, hence the development in this sector of UV, extreme-UV, and X-ray versions of the technique. However, an important aspect of diffraction-limited photolithography is not just the lateral dimensions of the point, but the axial dimension as well. For standard methods, the axial size of the point can be about twice that of either of the lateral dimensions, leading to an anisotropic (or non-symmetric) point-volume, and thus limiting the kinds of structures, which can be written. Hence, I am helping to develop a setup capable of 3-dimensionally isotropic (spherical point) writing of diffraction-limited structures.

Biography

Originally from the U.S., I traveled to Scotland to attend the University of St Andrews and complete my MPhys degree in 2010 in Physics with Photonics (the degree includes undergraduate years).

Afterward, I returned to the U.S. and spent about year building lasers for Photonics Industries Intl. in Bohemia, NY, gaining practical experience with nanosecond pulsed lasers operating in the infrared, visible, and UV.

In Sept 2011, I returned to the UK and undertook my PhD with Profs Paola Borri and Wolfgang Langbein. I completed my PhD in Sept 2015 (graduation 2016).

Since 2017, I have been a postdoc working on various projects under Profs Borri & Langbein, Prof Langbein and Dr. Sam Ladak, and Dr. Francesco Masia, with topics including linear optical microscopy of nanoparticles for nanoparticle characterisation, non-linear optical microscopy of living cells (algae), direct laser writing of diffraction-limited structures, and optical setup design/construction for optoelectronic device development. I joined the Cardiff Water Research Institute in 2022. I am currently Co-I of a research project concerning linear optical microscopy of liposomes for size characterisation of non-absorbing sub-500nm structures.